Fig 2. Development of the key nutrients (N, P, K) for plant production in the fish (RAS) and hydroponic (Hydro) units of the coupled (RAS C/Hydro C) and decoupled (RAS D, Hydro D) aquaponic system compared to the control (RAS A) over 22 weeks.

Nutrients in RAS C correspond to the nutrients in Hydro C since both are arranged as coupled aquaponic system. Recommended nutrient requirements for tomato production are indicated (dashed line).